Spark-plug



. c; G. PEIRCE.

SPARK PLUG. APPLICATION FILED APR. 30 1921.

2* 2 1 2 TL 1- I I v w z II a j 6 222 i 425/ 6 p v lNVENTOR" Cz' fardjzirce BY ATTORNEY p (5m UNITED STATES CLIFFORD G. PEIRCE, OF JERSEY CITY, NEW JERSEY.

SPARK-PLUG.

Specification of Letters Patent.

Patented Nov. 22, 1921.

Application filed April 30, 1921. Serial No. 465,629.

To all whom it may concern:

Be it known that I, CLIFFORD G. PnIRoE, a citizen of the United States, and resident of Jersey (lit in the county of Hudson and State of N ew Jersey, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specification.

The object of my invention is to provide a spark plug for internal combustion engines with a movable member slidable along the central or positive electrode, normally positioned opposite the negative or side electrode for normal operation of the spark therebetween, whereby when explosion occurs wlthin the engine cylinder said member will be automatically moved along the positive electrode, exposing the latter to the spark, the length of the spark between said electrodes thereby being lengthened. Said member wlll return to normal position after explosion ceases. The sliding of said member along the positive electrode serves to prevent the accumulation of soot thereon. When the insulation for the positive electrode is provided with a recess around said electrode said member will close the open end of said recess when explosion occurs to resist accumulation of soot within said recess. 7

My invention comprises novel details of improvement that will be more fully hereinafter set forth and then pointed out in the claims. 7

Reference is to be had to the accompanying drawings forming part hereof, wherein- Figure 1 is a artly sectional view of a spark plug embo ying my invention; Fig. 2

. is a view illustrating the movable member in the position it will assume upon explosion in an engine, and Fig. 3 is a detail plan view partly in section on line 3, 3 in Fig. 1.

The numeral 1 indicates the metal threaded base or casing of the plug to screw into an engine cylinder, 2 indicates the insulator carrying the positive or central electrode 3, and 4 indicates the negative or side electrode attached to base 1 and projecting toward electrode 3. V Insulator 2 may be of procelain, mica or other suitable material for the purpose, and may be held on base 1 by nut 5, Min any other suitable way usual in spark plugs. The spark plug illustrated is of ordinary form and construction. Slidable upon electrode 3 beyond the inner end of insulator 2 is a member 6 retained in normal position, with the plug vertically disposed, by a stop or head 3 on electrode 3, so that said member w1ll be opposite the laterally disposed end 4 of electrode 4, and suitably spaced therefrom for the jump of the spark between said member and the sparking tip or end of electrode 4 under usual normal conditions of use, Fig. 1.. In the last named position the member 6 is spaced below the inner end 2 of insulator 2 such a distance that said member may slide up along electrode 3, before engaging insulator 2, so that the spark will be broken from between electrode 4 and member 6 and will transfer to electrode 3 and jump between the latter and electrode 4. By preference the lower end of member 6 is tapered or beveled inwardly at 6 to cause the spark to gradually pass from member 6 to electrode 3 during the rise of said member. The member 6 is shown provided at its upper end with a lateral flange or head 6 slidable within lower bore 1 of base 1 in position to engage the end 2 of insulator 2, the lower part of the member being exposed to the spark. When said insulation is provided with an open recess 2 at its inner end, spaced from electrode 3, the member 6 will close said recess to' resist or'prevent the entrance of soot or products of combustion, as illustrated in Fig. 2.

When the plug is attached to an engine cylinder, in the vertical position, (Fig. 1), member 6 will be normally retained by sto 3 opposite and spaced from electrode 4, the sparking space being suitable and not too great for normal operation of starting the jump of the spark. When the spark operates between member 6 .and electrode 4 and explosion in the cylinder occurs the explosion pressure will operate on flange 6 and cause member 6 to slide upwardly along electrode 3, to be stopped by insulator 2, the bore in member 6 being sufiiciently large to permit free sliding of the member on said electrode. As member 6 rises the spark will follow said member until the distance between the sparking end of the electrode 4 and member 6 is too great whereupon the spark will transfer. to electrode 3. The spark will, therefore, be lengthened or drawn out, with the advantage resulting from a long, hot spark well known in the art. A lengthened or drawn out spark may be longer than is desirable for a spark at the plug terminals when the circuit is broken at the breaker points, since if the gap at the terminal or spark points is too great at such time the trode 3, due to reciprocation or vibration,

firing of the explosive charge in the engine cylinder is not usually at the best, if occurring at all. \Vith my invention the spark commences with proper length to be automatically lengthened. After member 6 has moved from between the electrodes the spark may jump from flange 6 within the base to the latter. Member 6 may rotate on elecpresenting fresh surfaces to the spark from time to time.

Having now described my invention, what I claim is r 1. A spark plug provided with means to automatically lengthen the spark between its terminals upon an explosion of gases occurring in contact with the plug.

2. A spark plug having a central electrode and an electrode opposed thereto, a member movable along the central electrode, and means normally retaining said member between the electrodesfor the passage of the spark between said member and the oppo site electrode, said member being adapted to move relatively to the electrodes to permit the spark to operate therebetween.

3. A spark plug having a central electrode and an electrode opposed thereto, a member movable along the central electrode, and means normally retaining said member between the electrodes for the passage of the spark between said member and the opposite electrode, said member being adapted to move relatively to the electrodes to'permit the spark to operate therebetween, said member having a reduced lower portion. a

4. A spark plug having a plurality of electrodes, a member movable along one of said electrodes, and means normally retaming said member between the electrodes for the passage of the spark between said member and one of said electrodes, said member having a flange at its upper portion to receive explosion pressureto cause the lower part of the member to pass from between said electrodes to permit the spark to operate therebetween.

5. A spark plug comprising a base having an electrode and a lower bore, an insulator extending into said bore and having an electrode' extending-through said bore spaced from the first named electrode, a member slidable on the second named electrode and spaced from said first namedelectrode for the passage of a spark therebetween, said electrodes being so spaced that the spark will jump therebetween when said member has moved from position between said electrodes. 6. A spark plug comprising a base having 'a' side electrode and a lower bore, an intral electrode extending beyond the first named electrode, spaced therefrom and having an outer stop, and a member slidable on the central electrodeand normally retained by said stop opposite and spaced from the first named electrode to be moved away therefrom. to increase the sparking gap between the electrodes;

Signed at New York city, in the'county of New York,'and State of New York, this 28th day of April A. D. 1921.

' CLIFFORD G. PEIRCE. 

